SwiftUI Picker在点击时不改变选择

Posted 2023-02-23

【中文标题】SwiftUI Picker在点击时不改变选择

【英文标题】：SwiftUI Picker not changing selection when tapped

【发布时间】：2021-03-27 10:15:18

【问题描述】：

这是我的对象列表：

let gameTypes = [
    GameType(id: "generalKnowledge", text: "❓ General Knowledge"),
    GameType(id: "geography", text: "???? Geography"),
    GameType(id: "music", text: "???? Music"),
    GameType(id: "sport", text: "⚽️ Sport"),
    GameType(id: "technology", text: "???? Technology"),
    GameType(id: "movies", text: "???? Movies & TV"),
]

在我看来，我的Picker：

@State var gameType: GameType = gameTypes[0]

var body: some View 
    NavigationView 
        VStack 
            // Create game
            HStack 
                Picker("\(gameType.text)", selection: $gameType) 
                    ForEach(gameTypes, id: \.id) type in
                        Text("\(type.text)").tag("\(type.id)")
                    
                
                .pickerStyle(MenuPickerStyle())

点击时，我的Picker 成功显示列表/菜单中的所有gameTypes 项目。但是，当我点击该列表中的某个项目时，gameType 不会更新。

知道为什么吗？

编辑：

游戏类型

class GameType: Hashable, Equatable 
    let id: String
    let text: String
    
    init(id: String, text: String) 
        self.id = id
        self.text = text
    
    
    // Conform to Hashable
    func hash(into hasher: inout Hasher) 
        hasher.combine(id)
    
    
    // Conform to Equatable (players will not be the same)
    static func == (lhs: GameType, rhs: GameType) -> Bool 
        return false
    

【问题讨论】：

什么是游戏类型？你能显示它的代码吗？

抱歉，添加到编辑@TusharSharma

【参考方案1】：

这是因为 GameType 和 Tag 类型不同。并且在选择时，swift 无法将Int 分配给GameType 类型。 只需将您的标签更改为type 而不是type.id，一切都会正常工作。 示例

HStack 
         Picker("\(gameType.text)", selection: $gameType) 
            ForEach(gameTypes, id: \.id)  type in
                 Text("\(type.text)").tag(type)
            
         
         .pickerStyle(MenuPickerStyle())
     

【参考方案2】：

这里有救命之恩，需要用struc：

---

---

struct GameType: Hashable, Identifiable, Equatable 
    
    let id: String
    let text: String
    
    init(id: String, text: String) 
        self.id = id
        self.text = text
    
    
    static func == (lhs: GameType, rhs: GameType) -> Bool 
        return lhs.id == rhs.id
    



let gameTypes = [
    GameType(id: "generalKnowledge", text: "❓ General Knowledge"),
    GameType(id: "geography", text: "? Geography"),
    GameType(id: "music", text: "? Music"),
    GameType(id: "sport", text: "⚽️ Sport"),
    GameType(id: "technology", text: "? Technology"),
    GameType(id: "movies", text: "? Movies & TV"),
]

---

import SwiftUI

struct ContentView: View 

    @State var gameTypeSelected: String = gameTypes[3].id
    
    var body: some View 

        Picker(selection: $gameTypeSelected, label: Text("")) 
  
            ForEach(gameTypes, id: \.id)  item in
                
                Text(item.text).id(item.id)
            

        
        
        Text("You selected: " + gameTypeSelected).bold()